#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

'''Implementation of SQLAlchemy backend.'''
from datetime import datetime
from datetime import timedelta
import sys

from oslo.config import cfg
import sqlalchemy
from sqlalchemy import orm
from sqlalchemy.orm.session import Session

from heat.common import crypt
from heat.common import exception
from heat.db.sqlalchemy import filters as db_filters
from heat.db.sqlalchemy import migration
from heat.db.sqlalchemy import models
from heat.openstack.common.db.sqlalchemy import session as db_session
from heat.openstack.common.db.sqlalchemy import utils
from heat.openstack.common.gettextutils import _

cfg.CONF.import_opt('max_events_per_stack', 'heat.common.config')

CONF = cfg.CONF
CONF.import_opt('max_events_per_stack', 'heat.common.config')
CONF.import_opt('connection', 'heat.openstack.common.db.options',
                group='database')

_facade = None


def get_facade():
    global _facade

    if not _facade:
        _facade = db_session.EngineFacade(
            CONF.database.connection, **dict(CONF.database.iteritems()))
    return _facade

get_engine = lambda: get_facade().get_engine()
get_session = lambda: get_facade().get_session()


def get_backend():
    """The backend is this module itself."""
    return sys.modules[__name__]


def model_query(context, *args):
    session = _session(context)
    query = session.query(*args)

    return query


def soft_delete_aware_query(context, *args, **kwargs):
    """Stack query helper that accounts for context's `show_deleted` field.

    :param show_deleted: if True, overrides context's show_deleted field.
    """

    query = model_query(context, *args)
    show_deleted = kwargs.get('show_deleted') or context.show_deleted

    if not show_deleted:
        query = query.filter_by(deleted_at=None)

    return query


def _session(context):
    return (context and context.session) or get_session()


def raw_template_get(context, template_id):
    result = model_query(context, models.RawTemplate).get(template_id)

    if not result:
        raise exception.NotFound(_('raw template with id %s not found') %
                                 template_id)

    return result


def raw_template_create(context, values):
    raw_template_ref = models.RawTemplate()
    raw_template_ref.update(values)
    raw_template_ref.save(_session(context))
    return raw_template_ref


def resource_get(context, resource_id):
    result = model_query(context, models.Resource).get(resource_id)

    if not result:
        raise exception.NotFound(_("resource with id %s not found") %
                                 resource_id)

    return result


def resource_get_by_name_and_stack(context, resource_name, stack_id):
    result = model_query(context, models.Resource).\
        filter_by(name=resource_name).\
        filter_by(stack_id=stack_id).\
        options(orm.joinedload("data")).first()

    return result


def resource_get_by_physical_resource_id(context, physical_resource_id):
    results = (model_query(context, models.Resource)
               .filter_by(nova_instance=physical_resource_id)
               .all())

    for result in results:
        if context is None or context.tenant_id in (
                result.stack.tenant, result.stack.stack_user_project_id):
            return result

    return None


def resource_get_all(context):
    results = model_query(context, models.Resource).all()

    if not results:
        raise exception.NotFound(_('no resources were found'))

    return results


def resource_data_get_all(resource, data=None):
    """
    Looks up resource_data by resource.id.  If data is encrypted,
    this method will decrypt the results.
    """
    if data is None:
        data = (model_query(resource.context, models.ResourceData)
                .filter_by(resource_id=resource.id))

    if not data:
        raise exception.NotFound(_('no resource data found'))

    ret = {}

    for res in data:
        if res.redact:
            ret[res.key] = _decrypt(res.value, res.decrypt_method)
        else:
            ret[res.key] = res.value

    return ret


def resource_data_get(resource, key):
    """Lookup value of resource's data by key. Decrypts resource data if
    necessary.
    """
    result = resource_data_get_by_key(resource.context,
                                      resource.id,
                                      key)
    if result.redact:
        return _decrypt(result.value, result.decrypt_method)
    return result.value


def _encrypt(value):
    if value is not None:
        return crypt.encrypt(value.encode('utf-8'))
    else:
        return None, None


def _decrypt(enc_value, method):
    if method is None:
        return None
    decryptor = getattr(crypt, method)
    value = decryptor(enc_value)
    if value is not None:
        return unicode(value, 'utf-8')


def resource_data_get_by_key(context, resource_id, key):
    """Looks up resource_data by resource_id and key. Does not unencrypt
    resource_data.
    """
    result = (model_query(context, models.ResourceData)
              .filter_by(resource_id=resource_id)
              .filter_by(key=key).first())

    if not result:
        raise exception.NotFound(_('No resource data found'))
    return result


def resource_data_set(resource, key, value, redact=False):
    """Save resource's key/value pair to database."""
    if redact:
        method, value = _encrypt(value)
    else:
        method = ''
    try:
        current = resource_data_get_by_key(resource.context, resource.id, key)
    except exception.NotFound:
        current = models.ResourceData()
        current.key = key
        current.resource_id = resource.id
    current.redact = redact
    current.value = value
    current.decrypt_method = method
    current.save(session=resource.context.session)
    return current


def resource_exchange_stacks(context, resource_id1, resource_id2):
    query = model_query(context, models.Resource)
    session = query.session
    session.begin()

    res1 = query.get(resource_id1)
    res2 = query.get(resource_id2)

    res1.stack, res2.stack = res2.stack, res1.stack

    session.commit()


def resource_data_delete(resource, key):
    result = resource_data_get_by_key(resource.context, resource.id, key)
    result.delete()


def resource_create(context, values):
    resource_ref = models.Resource()
    resource_ref.update(values)
    resource_ref.save(_session(context))
    return resource_ref


def resource_get_all_by_stack(context, stack_id):
    results = model_query(context, models.Resource).\
        filter_by(stack_id=stack_id).\
        options(orm.joinedload("data")).all()

    if not results:
        raise exception.NotFound(_("no resources for stack_id %s were found")
                                 % stack_id)

    return dict((res.name, res) for res in results)


def stack_get_by_name_and_owner_id(context, stack_name, owner_id):
    query = soft_delete_aware_query(context, models.Stack).\
        filter(sqlalchemy.or_(
            models.Stack.tenant == context.tenant_id,
            models.Stack.stack_user_project_id == context.tenant_id
        )).\
        filter_by(name=stack_name).\
        filter_by(owner_id=owner_id)

    return query.first()


def stack_get_by_name(context, stack_name):
    query = soft_delete_aware_query(context, models.Stack).\
        filter(sqlalchemy.or_(
            models.Stack.tenant == context.tenant_id,
            models.Stack.stack_user_project_id == context.tenant_id
        )).\
        filter_by(name=stack_name)

    return query.first()


def stack_get(context, stack_id, show_deleted=False, tenant_safe=True,
              eager_load=False):
    query = model_query(context, models.Stack)
    if eager_load:
        query = query.options(orm.joinedload("raw_template"))
    result = query.get(stack_id)

    deleted_ok = show_deleted or context.show_deleted
    if result is None or result.deleted_at is not None and not deleted_ok:
        return None

    # One exception to normal project scoping is users created by the
    # stacks in the stack_user_project_id (in the heat stack user domain)
    if (tenant_safe and result is not None and context is not None and
        context.tenant_id not in (result.tenant,
                                  result.stack_user_project_id)):
        return None

    return result


def stack_get_all_by_owner_id(context, owner_id):
    results = soft_delete_aware_query(context, models.Stack).\
        filter_by(owner_id=owner_id).all()
    return results


def _filter_sort_keys(sort_keys, whitelist):
    '''Returns an array containing only whitelisted keys

    :param sort_keys: an array of strings
    :param whitelist: an array of allowed strings
    :returns: filtered list of sort keys
    '''
    if not sort_keys:
        return []
    elif not isinstance(sort_keys, list):
        sort_keys = [sort_keys]

    return [key for key in sort_keys if key in whitelist]


def _paginate_query(context, query, model, limit=None, sort_keys=None,
                    marker=None, sort_dir=None):
    default_sort_keys = ['created_at']
    if not sort_keys:
        sort_keys = default_sort_keys
        if not sort_dir:
            sort_dir = 'desc'

    # This assures the order of the stacks will always be the same
    # even for sort_key values that are not unique in the database
    sort_keys = sort_keys + ['id']

    model_marker = None
    if marker:
        model_marker = model_query(context, model).get(marker)
    try:
        query = utils.paginate_query(query, model, limit, sort_keys,
                                     model_marker, sort_dir)
    except utils.InvalidSortKey as exc:
        raise exception.Invalid(reason=exc.message)

    return query


def _query_stack_get_all(context, tenant_safe=True, show_deleted=False):
    query = soft_delete_aware_query(context, models.Stack,
                                    show_deleted=show_deleted).\
        filter_by(owner_id=None)

    if tenant_safe:
        query = query.filter_by(tenant=context.tenant_id)

    return query


def stack_get_all(context, limit=None, sort_keys=None, marker=None,
                  sort_dir=None, filters=None, tenant_safe=True,
                  show_deleted=False):
    query = _query_stack_get_all(context, tenant_safe,
                                 show_deleted=show_deleted)
    return _filter_and_page_query(context, query, limit, sort_keys,
                                  marker, sort_dir, filters).all()


def _filter_and_page_query(context, query, limit=None, sort_keys=None,
                           marker=None, sort_dir=None, filters=None):
    if filters is None:
        filters = {}

    allowed_sort_keys = [models.Stack.name.key,
                         models.Stack.status.key,
                         models.Stack.created_at.key,
                         models.Stack.updated_at.key]
    whitelisted_sort_keys = _filter_sort_keys(sort_keys, allowed_sort_keys)

    query = db_filters.exact_filter(query, models.Stack, filters)
    return _paginate_query(context, query, models.Stack, limit,
                           whitelisted_sort_keys, marker, sort_dir)


def stack_count_all(context, filters=None, tenant_safe=True):
    query = _query_stack_get_all(context, tenant_safe=tenant_safe)
    query = db_filters.exact_filter(query, models.Stack, filters)
    return query.count()


def stack_create(context, values):
    stack_ref = models.Stack()
    stack_ref.update(values)
    stack_ref.save(_session(context))
    return stack_ref


def stack_update(context, stack_id, values):
    stack = stack_get(context, stack_id)

    if not stack:
        raise exception.NotFound(_('Attempt to update a stack with id: '
                                 '%(id)s %(msg)s') % {
                                     'id': stack_id,
                                     'msg': 'that does not exist'})

    stack.update(values)
    stack.save(_session(context))


def stack_delete(context, stack_id):
    s = stack_get(context, stack_id)
    if not s:
        raise exception.NotFound(_('Attempt to delete a stack with id: '
                                 '%(id)s %(msg)s') % {
                                     'id': stack_id,
                                     'msg': 'that does not exist'})

    session = Session.object_session(s)

    for r in s.resources:
        session.delete(r)

    s.soft_delete(session=session)

    session.flush()


def stack_lock_create(stack_id, engine_id):
    session = get_session()
    with session.begin():
        lock = session.query(models.StackLock).get(stack_id)
        if lock is not None:
            return lock.engine_id
        session.add(models.StackLock(stack_id=stack_id, engine_id=engine_id))


def stack_lock_steal(stack_id, old_engine_id, new_engine_id):
    session = get_session()
    with session.begin():
        lock = session.query(models.StackLock).get(stack_id)
        rows_affected = session.query(models.StackLock).\
            filter_by(stack_id=stack_id, engine_id=old_engine_id).\
            update({"engine_id": new_engine_id})
    if not rows_affected:
        return lock.engine_id if lock is not None else True


def stack_lock_release(stack_id, engine_id):
    session = get_session()
    with session.begin():
        rows_affected = session.query(models.StackLock).\
            filter_by(stack_id=stack_id, engine_id=engine_id).\
            delete()
    if not rows_affected:
        return True


def user_creds_create(context):
    values = context.to_dict()
    user_creds_ref = models.UserCreds()
    if values.get('trust_id'):
        method, trust_id = _encrypt(values.get('trust_id'))
        user_creds_ref.trust_id = trust_id
        user_creds_ref.decrypt_method = method
        user_creds_ref.trustor_user_id = values.get('trustor_user_id')
        user_creds_ref.username = None
        user_creds_ref.password = None
        user_creds_ref.tenant = values.get('tenant')
        user_creds_ref.tenant_id = values.get('tenant_id')
    else:
        user_creds_ref.update(values)
        method, password = _encrypt(values['password'])
        user_creds_ref.password = password
        user_creds_ref.decrypt_method = method
    user_creds_ref.save(_session(context))
    return user_creds_ref


def user_creds_get(user_creds_id):
    db_result = model_query(None, models.UserCreds).get(user_creds_id)
    if db_result is None:
        return None
    # Return a dict copy of db results, do not decrypt details into db_result
    # or it can be committed back to the DB in decrypted form
    result = dict(db_result)
    del result['decrypt_method']
    result['password'] = _decrypt(result['password'], db_result.decrypt_method)
    result['trust_id'] = _decrypt(result['trust_id'], db_result.decrypt_method)
    return result


def user_creds_delete(context, user_creds_id):
    creds = model_query(context, models.UserCreds).get(user_creds_id)
    if not creds:
        raise exception.NotFound(
            _('Attempt to delete user creds with id '
              '%(id)s that does not exist') % {'id': user_creds_id})
    session = Session.object_session(creds)
    session.delete(creds)
    session.flush()


def event_get(context, event_id):
    result = model_query(context, models.Event).get(event_id)

    return result


def event_get_all(context):
    stacks = soft_delete_aware_query(context, models.Stack)
    stack_ids = [stack.id for stack in stacks]
    results = model_query(context, models.Event).\
        filter(models.Event.stack_id.in_(stack_ids)).all()

    return results


def event_get_all_by_tenant(context):
    stacks = soft_delete_aware_query(context, models.Stack).\
        filter_by(tenant=context.tenant_id).all()
    results = []
    for stack in stacks:
        results.extend(model_query(context, models.Event).
                       filter_by(stack_id=stack.id).all())

    return results


def _query_all_by_stack(context, stack_id):
    query = model_query(context, models.Event).\
        filter_by(stack_id=stack_id)
    return query


def event_get_all_by_stack(context, stack_id):
    return _query_all_by_stack(context, stack_id).order_by(
        models.Event.id).all()


def event_count_all_by_stack(context, stack_id):
    return _query_all_by_stack(context, stack_id).count()


def _delete_event_rows(context, stack_id, limit):
    # MySQL does not support LIMIT in subqueries,
    # sqlite does not support JOIN in DELETE.
    # So we must manually supply the IN() values.
    # pgsql SHOULD work with the pure DELETE/JOIN below but that must be
    # confirmed via integration tests.
    query = _query_all_by_stack(context, stack_id)
    session = _session(context)
    if 'postgres' not in session.connection().dialect.name:
        ids = [r.id for r in query.order_by(
            models.Event.id).limit(limit).all()]
        q = session.query(models.Event).filter(
            models.Event.id.in_(ids))
    else:
        stmt = session.query(
            models.Event.id).filter_by(
                stack_id=stack_id).order_by(
                    models.Event.id).limit(limit).subquery()
        q = query.join(stmt, models.Event.id == stmt.c.id)
    return q.delete(synchronize_session='fetch')


def event_create(context, values):
    if 'stack_id' in values and cfg.CONF.max_events_per_stack:
        if ((event_count_all_by_stack(context, values['stack_id']) >=
             cfg.CONF.max_events_per_stack)):
            # prune
            _delete_event_rows(
                context, values['stack_id'], cfg.CONF.event_purge_batch_size)
    event_ref = models.Event()
    event_ref.update(values)
    event_ref.save(_session(context))
    return event_ref


def watch_rule_get(context, watch_rule_id):
    result = model_query(context, models.WatchRule).get(watch_rule_id)
    return result


def watch_rule_get_by_name(context, watch_rule_name):
    result = model_query(context, models.WatchRule).\
        filter_by(name=watch_rule_name).first()
    return result


def watch_rule_get_all(context):
    results = model_query(context, models.WatchRule).all()
    return results


def watch_rule_get_all_by_stack(context, stack_id):
    results = model_query(context, models.WatchRule).\
        filter_by(stack_id=stack_id).all()
    return results


def watch_rule_create(context, values):
    obj_ref = models.WatchRule()
    obj_ref.update(values)
    obj_ref.save(_session(context))
    return obj_ref


def watch_rule_update(context, watch_id, values):
    wr = watch_rule_get(context, watch_id)

    if not wr:
        raise exception.NotFound(_('Attempt to update a watch with id: '
                                 '%(id)s %(msg)s') % {
                                     'id': watch_id,
                                     'msg': 'that does not exist'})

    wr.update(values)
    wr.save(_session(context))


def watch_rule_delete(context, watch_id):
    wr = watch_rule_get(context, watch_id)
    if not wr:
        raise exception.NotFound(_('Attempt to delete watch_rule: '
                                 '%(id)s %(msg)s') % {
                                     'id': watch_id,
                                     'msg': 'that does not exist'})
    session = Session.object_session(wr)

    for d in wr.watch_data:
        session.delete(d)

    session.delete(wr)
    session.flush()


def watch_data_create(context, values):
    obj_ref = models.WatchData()
    obj_ref.update(values)
    obj_ref.save(_session(context))
    return obj_ref


def watch_data_get_all(context):
    results = model_query(context, models.WatchData).all()
    return results


def software_config_create(context, values):
    obj_ref = models.SoftwareConfig()
    obj_ref.update(values)
    obj_ref.save(_session(context))
    return obj_ref


def software_config_get(context, config_id):
    result = model_query(context, models.SoftwareConfig).get(config_id)
    if (result is not None and context is not None and
            result.tenant != context.tenant_id):
        result = None

    if not result:
        raise exception.NotFound(_('Software config with id %s not found') %
                                 config_id)
    return result


def software_config_delete(context, config_id):
    config = software_config_get(context, config_id)
    session = Session.object_session(config)
    session.delete(config)
    session.flush()


def software_deployment_create(context, values):
    obj_ref = models.SoftwareDeployment()
    obj_ref.update(values)
    obj_ref.save(_session(context))
    return obj_ref


def software_deployment_get(context, deployment_id):
    result = model_query(context, models.SoftwareDeployment).get(deployment_id)
    if (result is not None and context is not None and
        context.tenant_id not in (result.tenant,
                                  result.stack_user_project_id)):
        result = None

    if not result:
        raise exception.NotFound(_('Deployment with id %s not found') %
                                 deployment_id)
    return result


def software_deployment_get_all(context, server_id=None):
    sd = models.SoftwareDeployment
    query = model_query(context, sd).\
        filter(sqlalchemy.or_(
            sd.tenant == context.tenant_id,
            sd.stack_user_project_id == context.tenant_id
        )).\
        order_by(sd.created_at)
    if server_id:
        query = query.filter_by(server_id=server_id)
    return query.all()


def software_deployment_update(context, deployment_id, values):
    deployment = software_deployment_get(context, deployment_id)
    deployment.update(values)
    deployment.save(_session(context))
    return deployment


def software_deployment_delete(context, deployment_id):
    deployment = software_deployment_get(context, deployment_id)
    session = Session.object_session(deployment)
    session.delete(deployment)
    session.flush()


def snapshot_create(context, values):
    obj_ref = models.Snapshot()
    obj_ref.update(values)
    obj_ref.save(_session(context))
    return obj_ref


def snapshot_get(context, snapshot_id):
    result = model_query(context, models.Snapshot).get(snapshot_id)
    if (result is not None and context is not None and
            context.tenant_id != result.tenant):
        result = None

    if not result:
        raise exception.NotFound(_('Snapshot with id %s not found') %
                                 snapshot_id)
    return result


def snapshot_update(context, snapshot_id, values):
    snapshot = snapshot_get(context, snapshot_id)
    snapshot.update(values)
    snapshot.save(_session(context))
    return snapshot


def snapshot_delete(context, snapshot_id):
    snapshot = snapshot_get(context, snapshot_id)
    session = Session.object_session(snapshot)
    session.delete(snapshot)
    session.flush()


def purge_deleted(age, granularity='days'):
    try:
        age = int(age)
    except ValueError:
        raise exception.Error(_("age should be an integer"))
    if age < 0:
        raise exception.Error(_("age should be a positive integer"))

    if granularity not in ('days', 'hours', 'minutes', 'seconds'):
        raise exception.Error(
            _("granularity should be days, hours, minutes, or seconds"))

    if granularity == 'days':
        age = age * 86400
    elif granularity == 'hours':
        age = age * 3600
    elif granularity == 'minutes':
        age = age * 60

    time_line = datetime.now() - timedelta(seconds=age)
    engine = get_engine()
    meta = sqlalchemy.MetaData()
    meta.bind = engine

    stack = sqlalchemy.Table('stack', meta, autoload=True)
    event = sqlalchemy.Table('event', meta, autoload=True)
    raw_template = sqlalchemy.Table('raw_template', meta, autoload=True)
    user_creds = sqlalchemy.Table('user_creds', meta, autoload=True)

    stmt = sqlalchemy.select([stack.c.id,
                              stack.c.raw_template_id,
                              stack.c.user_creds_id]).\
        where(stack.c.deleted_at < time_line)
    deleted_stacks = engine.execute(stmt)

    for s in deleted_stacks:
        event_del = event.delete().where(event.c.stack_id == s[0])
        engine.execute(event_del)
        stack_del = stack.delete().where(stack.c.id == s[0])
        engine.execute(stack_del)
        raw_template_del = raw_template.delete().\
            where(raw_template.c.id == s[1])
        engine.execute(raw_template_del)
        user_creds_del = user_creds.delete().where(user_creds.c.id == s[2])
        engine.execute(user_creds_del)


def db_sync(engine, version=None):
    """Migrate the database to `version` or the most recent version."""
    return migration.db_sync(engine, version=version)


def db_version(engine):
    """Display the current database version."""
    return migration.db_version(engine)
